Young men who have sex with men (YMSM) are the only risk group with a rising incidence of HIV infection, yet a high proportion of HIV-infected YMSM are unaware of their seropositive status. HIV testing is the critical first component of HIV prevention and care. Individuals who are aware of their infection can begin treatment, which can reduce the likelihood of onward transmission and improve clinical outcomes. Barriers to testing among youth-including YMSM-include perception of low risk, fear of testing positive, concerns about confidentiality and accessibility to health services. Virtual reality (VR) and intelligent virtual agent technologies can provide youth with the ability to experience all aspecs of the testing process thus overcoming many of the basic barriers to access and effective care. VR can offer realistic sensory cues such as sounds, sights, and rich, interactive dialogue that would be expected to elicit more affect in YMSM than simply watching a video vignette. Our project, Test Rehearsal: Maximizing the HIV Testing Experience for YMSM, will create a secure, internet-delivered software program, available by mobile devices that will offer character-driven realistic scenarios that are engaging, interactive, ecologically sensitive, and user-centric in content and design allowing youth to actively experience the HIV testing process in a non-threatening and non-stigmatizing environment. Test Rehearsal is theoretically grounded within the Information, Motivation and Behavioral (IMB) model and will be a novel and high impact prevention tool to address the lack of uptake of HIV testing among YMSM 14-19 years of age. This project builds logically on previous work including VR cue exposure for health- related behaviors, creation and testing of VR technology for at-risk youth (i.e. HIV, substance use), formative work and content development with the target population (i.e. disclosure of HIV status among HIV+ YMSM) and creation, development and testing of mHealth interventions for YMSM (including those focused on linkage and retention in care and adherence to antiretroviral therapy). The goals of this Phase I SBIR are to develop and evaluate content of a complete VR affect-inducing HIV self-testing scenario informed by both online and in-person focus-groups with 24-32 YMSM, and to assess the feasibility, acceptability, and usability of the prototype with 12-15 YMSM who are not frequent testers. If successful, Phase II will support the full development of Test Rehearsal, a complete, mHealth HIV testing and linkage to care intervention for YMSM. The intervention will include introductory assessment modules (e.g., that educate on the benefits of testing, types of tests available (e.g. self-testing clinic, couples counseling), skill-based tools designed to facilitate more open communication around testing including discussions of sexual risk among users and testing providers, and feedback modules based on intelligent virtual agent-driven practice scenarios to aid youth in making testing decisions and experiencing the testing process.